1. Field of the Invention
The present invention relates to a soldering device for soldering components onto printed circuit boards, comprising at least two stirrup electrodes secured to a soldering stirrup holder and heatable by electrical resistance heating, and comprising a suction pipette arranged centrally between the stirrup electrodes for picking up, conveying and placing the components onto a signed soldering locations.
2. Description of the Prior Art
Soldering device having two stirrup electrodes lying parallel and opposite one another or having four stirrup electrodes lying opposite one another in pairs are particularly utilized for soldering electronic components having many terminals, such as micropacks, flat packs and the like. When such a soldering device is then additionally equipped to the suction pipette arranged centrally between the stirrup electrodes, the soldering device can then be utilized for the automatic equipping of printed circuit boards with the components to be soldering thereon. When equipping in accordance with what is referred to as the pick and place principle, the combined equipping and soldering head moves over the delivery modules of the components and over the printed circuit board arranged in the equipping region, whereby the suction pipette picks up the respective component from the delivery module and places it onto the printed circuit board in the prescribed equipping position. After placement of the respective component, the soldering stirrup holder is then lowered, so that an optimally reliable contact between the working surfaces of the stirrup electrodes, the terminal legs of the component and the interconnect or, respectively, the terminal pads of the printed circuit board results before the soldering process as well as over the entire duration of the soldering process. The suction pipette remains on the component until the end of the soldering process and thereby presses the component against the soldering location on the printed circuit board with a limited force.
During the soldering process initiated by the electrical resistance heating of the stirrup electrodes, solder vapors that can contain both volatile constituents such as dilutants of the employed fluxing agent and solid constituents of the employed fluxing agents such as, for example, colophonium arise. The solder vapors that already arise before the soldering temperature is reached then precipitate on colder locations of the soldering device, whereby this precipitation can lead to a destruction or at least to a considerable deterioration, particularly in the region of the mechanical guides, in the region of bearings or articulations and in the region of electrical contacts. A manual removal of the precipitation, as is still possible given an occasional employment of the soldering device, must be excluded given utilization of the soldering device in mass production.